Alfred w



(model.)

A W COCHRAN KNOTTER POR SEWING MACHINES.

Patented Oct. 16,1894.

UNITED STATES ALFRED W. COCHRAN OF NEW YORK, N. Y.

KNOTTER FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 527,407, dated October16, 1894.

Application tied August 8,1893. seritinaisasi. (Model.)

j To` all whom it mwyconcern:

4Be it known that I, ALFRED W. COCHRAN, a citizen of the UnitedStates,residing in the city and State of New York, have invented an Improvementin Knotters for Sewing-Machines, of which the following is aspecification.

In Letters Patent No. 453,730, granted to me June 9, 1891, a knotter isrepresented having two spring arms and located between the two sides ofa throat plate, so that by the rotation of the twister the lower orshuttle thread is twisted into a loop through which the needle passes,and then the shuttle thread is passed through the loop of needle threadand as the threads draw up, a knot is tied between the shuttle threadand the needle thread closely adjacent to the under side of the fabricthat is being sewed. In my present invention a similar knot is tied, butI have simplified the parts so as to lessen their expense and also torender the operation more positive and reliable.

I construct the twister with jaws, the eX- terior surfaces of which whenthe jaws are `closed form a cylinder between theupper and lower parts ofthe throat plate, and by the act of rotating the twister the spring-jawis closed against the rigid jaw around the thread, by the pressure ofsaid spring-jaw against one wall of the opening in the throat-plate,anda cam-slot andpin are provided for drawing back the jaws after theyhave been closed to seize the thread, in order that the parts of theloop may interlock at the end of the twister, and then the twister ismoved forward again and opens by the spring jaw to spread the twistedloop and hold the same `for the passage of the needle, after which theshuttle is passed through the loop of needle thread and the twisted loopof shuttle thread draws off the twister and is around the nee- 'dle anddraws up closely against the under the parts, also partially in section.Fig. 3 is a perspective view showing the twister as detached from thethroat plate and open to spread the loop, and Fig. 4 shows the twisteras closed and revolved halfway around. Fig. 5 is a diagram of the knot.Fig. 6 is a cross section, at the line w, Fig. l, and Fig. 7 is anelevation of the button head of the twister;`

The throat-plate A, is preferably formed of j a piece of metalsufficiently thick for a hole to be bored therein longitudinally andparallel with its upper and lower surfaces and an opening extends fromthis hole laterally to the edge of the plate thereby forming an upperplate 2, and a lower plate 5f, which are perforated with holes for thepassage of the needle, and the` twister B is formed of substantially acylindrical wire filling the hole in the throat plate and having abutton or head C at the outer end, and this button or head C isadvantageously circular except that the upper part thereof should be cutoff at the same level as the top surface of the throat` plate so as notto interfere with the fabric that is being sewed as the same lies uponthe surface of the throat plate, and by providing a notch at 4 in theend of the head, the twister may be rotated by inserting the nail in thenotch 4, pressing the twister inwardly against the action of the helicalspring D that surrounds the outer part of the twister shank, and in sodoing the circular portion of the head C is brought above the surface ofthe sewing machine table and can be rotated by pressure of the linger,so that it revolves once in twisting the thread, as hereinafterdescribed.

The throat plate (A) may be secured to the bed of the sewing machine inany convenient manner. Usually it is attached to the plate (A) that isscrewed to the bed of the sewing machine and has the openings for thefeed bar asusual. Across the projecting end of the throat plate is adiagonal slot or mortise at 5 within which is a pin 6 upon the shank ofthe twister; and it will be observed that this pin 6 as the twister isrotated and the pin travels in the slot 5 gives to the twister an endmovement bodily and then forces the twister back again into its normalposition, and by providing an offset or notch in the slot 5, as at 7,the twister is stopped each rotation in the proper position by the pinGpassing into said notch or offset at the com- IOO ceive its rotation.

pletion of the rotation, and the twister has to be pushed inwardlyagainst the action of the spring D before the pin 6 will clear theoffset 7 and hence before the twister can re This insures the inwardmovementwhich is advantageously given to the twister ir the act ofgrasping the thread. Through the upper and lower sides 2rand 3 of thethroat plate there are the holes 8 and 9 ro for the eye-pointed needleto pass through, and

these are in such a posit-ion that the jaws of the twister are atopposite sides of the needle as it passes through the holes; and it isto be understood that this throat plateY is se-V cured to the sewingmachine but with the upper surface of the throat plate on the level ornearly so` of the sewing machine bed and hence that the shuttle threadpasses up through the holes 8 and 9 as the lock stitch zo is drawn up ortightened in the fabric, and

3o forms a spring that tends to open the jaw end of the twister, and theexterior surfaces of the jaw ends of the twister are semi-cylindrical,and the opposite adjacent faces of the jaw ends are recessed so thatwhen the jaw 3 5 ends are brought together as in Fig. 4, there is anelongated mortise for the thread, and upon the spring jaw of the twisteris a hook i' 11' having its pointextending inwardly toward the mortise,and in the rigid side of the 4o jaw is a groove l2 running outwardlyfrom the mortise; and it will also be observed by Fig. 6 that the lowereye or hole 9 through H.the lower side 3 of the throat plate iselongated and beveled toward the rigid jaw, the

object being to prevent clamping and cutting the thread when the partsare rotated in twisting the shuttle thread. It is now to be understoodthat when an end motion is given to the twister, as before described,Vit passesVY 5o'toward the shuttle thread as the same extends throughthe two eyes or holes 8 and 9 of the throat plate, and as the twister isrotated the spring jaw thereof is closed by the semi-cylindrical surfacethereof sliding on the lower plate as the twister is rotated between theupper and lower sides of the throat plate, and the twister is closed sothat the thread is within the elongated slot of the twister.- In thisposition the ends of 6o the mortise through the twister extend as far asthe edges of the eyes 8 and 9, so that the thread cannot be caughtbetween the surfaces that come together but is free within the mortise,and as the rotation proceeds the twister is also drawn back by theaction of the diagonal slot and pin and one part ofthe thread passesinto the groove of the hook 1l and the other part of the thread passesout through the groove l2, as seen in Fig 4, and the twister draws backsufficiently for the Ytwo parts of the thread to twist together and ofthe hole 8,Y and out of the way of the de- Y scending needle, and theportion of the loop of thread that passes across from one hook l2, tothe other hook 1l, is near the other edge of the hole 8, so that theneedle passes freely through the loop. The loop of needle thread ispassed around theshuttle or the shuttle passed through the loop, asillustrated in Fig. 5, so that the twisted loop of shuttle thread drawsoff the twister by the tension and is around such eye-pointed needle andis shed oft' the needle against the under side of the fabric thatisbeing sewed as the needle draws up and the needle thread is drawn up,by the action of its tension, through the twisted loop of shuttle threaduntil the threads tighten and a knot similar to a sailors knot is tiedclosely adjacent tothe under side of the fabric that is being sewed. i

Itwill be observed that the metal of the throat plate that is adjacentto the rigid side of the twister when the twister is in the normalposition shown in Fig. l, keeps the spring side of the twister closed upagainst the rigid sideY of the twister when the parts have been halfrotated, as indicated 4in Fig. 4, and the respective grooves and hooksupon the jaws of the twister are in sucha position that the threadpasses out of the mortise of the twister into such grooves and the partsof the thread are held by the hooks in the grooves of the jaws, and whenthe twister has been revolved haltl way the twister has been drawn backby the pin and inclined slot so that the ends of the twister are backfrom the holes Sand 9, and the threads are obliged to twist'togetherbeyond the ends of the jaws as in Fig. 4, and as the twister completesits rotation it is roo -IIO

moved forward into the position -shown in` the'twisted loop, because thepart of the twisted loop that is around the spring jaw is free to passoff from the spring jaw, and the other part of the twisted loop betweenthe rigid jaw and the throat plate is only held with aslight frictionand the thread pulls out from that position by the friction of thetwisted loop around the eye-pointed needleas such eye-pointed needlerises; and it will be observed upon reference to Fig. 6, that the upperpart of the lower side of the throat plate around the lower eye 9, isbeveled to give ample room for the loop to east E from the spring jaw.The knot is completed as the threads are tightened as aforesaid.

By constructing the parts in the manner before described the operationsare rendered perfect and reliable and the en-d movement of the twisteris rendered as short as possible and the angle of the cam slot is suchthat the pin can be easily moved therein with but little friction. Theends of the jaws when closed being .cylindrical and filling the spacebetween the upper and lower sides prevent the thread slipping out fromthe hooks 11 and 12, and the thread draws over the hooks as the jawsopen and the loop is spread.

In some characters of sewing machines the cover plates over the shuttleraceway will come up at each side of the extending portion of the throatplate and also partially adjacent to the plate A', as illustrated at EF, Fig. 1.

I claim as my invention- 1. The combination with the throat plate,

with an opening for the passage of the eyefor the passage of theeye-pointed needle and` a longitudinal hole, of a rotatable twisterwithin such hole having one rigid and one spring jaw, the exterior ofthe springjaw being rounding so as to be closed in its rotation bycontact with the throat plate, the `jaws being recessed in their innerfaces to form. an elongated eye and having grooves and hooks at the endsof the jaws for'twisting the thread, and means for giving an endmovement to the twister as it is rotated, substantially as specified. j

3. The combination with the throat plate, of a twister formed of acylindrical wire split longitudinally and having a spring jaw, hooks andgrooves near the ends of the jaws, mechanism for giving an end movementof the twister as the same is rotated, a circular head upon the end ofthe twister with the upper edge removed to the level of the top of thethroat plate, and a notch for receiving the inger nail for rotating suchtwister,substan tially as set forth.

4.. The combination with the throat plate having upper and lower sides,with openings for the passage of the eye-pointed needle, a diagonal slotand a longitudinal hole, of a rotatable twister within such hole havingone rigid and one spring jaw, the exterior of the spring jaw beingrounding so as to be closed in its rotation by contact with the throatplate, the jaws being recessed in their inner faces to form an elongatedeye and having grooves and hooks at the ends of the jaws for i ALFRED W.COCHRAN.

Witnesses: j

GEO. T. PINCKNEY, A. M. OLIVER.

